The present application relates generally to an improved data processing apparatus and method and more specifically to mechanisms for volume swapping point-in-time read-only target volumes.
In known data processing systems, instantaneous point-in-time copy relationships may be established between a source volume and a target volume. At the time the instantaneous point-in-time relationship is established, the data processing system may atomically establish a second instantaneous point-in-time relationship between a continuous synchronous copy volume associated with the source volume and another target volume as well as establishing another continuous synchronous copy relationship between the target volumes. However, establishing both continuous synchronous copy relationships between the source volume and the continuous synchronous copy volume as well as between the target volumes requires significant set-up time, additional resources on and between the storage system, additional planning and monitoring by the operator (or application), additional bandwidth for the continuous synchronous copy paths, or the like. Further, additional storage system resources include the additional connections (paths) to copy the data and the additional bandwidth over the connections to complete a full copy of the target volumes. If the paths to copy the data are not direct connections, additional switching resources may also be required. As the instantaneous point-in-time copies may only be initiated when the continuous copy relationships are in a full duplex state, additional work is required to monitor the continuous copy relationships prior to initiating the instantaneous point-in-time copies.